Update from https://crrev.com/327068

base/threading/platform_thread_posix.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/threading/platform_thread.h"
 
 #include <errno.h>
 #include <pthread.h>
 #include <sched.h>
 #include <sys/resource.h>
@@ skipping 21 matching lines @@
 void InitOnThread();
 void TerminateOnThread();
 size_t GetDefaultThreadStackSize(const pthread_attr_t& attributes);
 
 namespace {
 
 struct ThreadParams {
   ThreadParams()
       : delegate(NULL),
         joinable(false),
-        priority(kThreadPriority_Normal),
+        priority(ThreadPriority::NORMAL),
         handle(NULL),
         handle_set(false, false) {
   }
 
   PlatformThread::Delegate* delegate;
   bool joinable;
   ThreadPriority priority;
   PlatformThreadHandle* handle;
   WaitableEvent handle_set;
 };
 
 void* ThreadFunc(void* params) {
   base::InitOnThread();
   ThreadParams* thread_params = static_cast<ThreadParams*>(params);
 
   PlatformThread::Delegate* delegate = thread_params->delegate;
   if (!thread_params->joinable)
     base::ThreadRestrictions::SetSingletonAllowed(false);
 
-  if (thread_params->priority != kThreadPriority_Normal) {
+  if (thread_params->priority != ThreadPriority::NORMAL) {
     PlatformThread::SetThreadPriority(PlatformThread::CurrentHandle(),
                                       thread_params->priority);
   }
 
   // Stash the id in the handle so the calling thread has a complete
   // handle, and unblock the parent thread.
   *(thread_params->handle) = PlatformThreadHandle(pthread_self(),
                                                   PlatformThread::CurrentId());
   thread_params->handle_set.Signal();
 
@@ skipping 121 matching lines @@
 // static
 const char* PlatformThread::GetName() {
   return ThreadIdNameManager::GetInstance()->GetName(CurrentId());
 }
 
 // static
 bool PlatformThread::Create(size_t stack_size, Delegate* delegate,
                             PlatformThreadHandle* thread_handle) {
   base::ThreadRestrictions::ScopedAllowWait allow_wait;
   return CreateThread(stack_size, true /* joinable thread */,
-                      delegate, thread_handle, kThreadPriority_Normal);
+                      delegate, thread_handle, ThreadPriority::NORMAL);
 }
 
 // static
 bool PlatformThread::CreateWithPriority(size_t stack_size, Delegate* delegate,
                                         PlatformThreadHandle* thread_handle,
                                         ThreadPriority priority) {
   base::ThreadRestrictions::ScopedAllowWait allow_wait;
   return CreateThread(stack_size, true,  // joinable thread
                       delegate, thread_handle, priority);
 }
 
 // static
 bool PlatformThread::CreateNonJoinable(size_t stack_size, Delegate* delegate) {
   PlatformThreadHandle unused;
 
   base::ThreadRestrictions::ScopedAllowWait allow_wait;
   bool result = CreateThread(stack_size, false /* non-joinable thread */,
-                             delegate, &unused, kThreadPriority_Normal);
+                             delegate, &unused, ThreadPriority::NORMAL);
   return result;
 }
 
 // static
 void PlatformThread::Join(PlatformThreadHandle thread_handle) {
   // Joining another thread may block the current thread for a long time, since
   // the thread referred to by |thread_handle| may still be running long-lived /
   // blocking tasks.
   base::ThreadRestrictions::AssertIOAllowed();
   CHECK_EQ(0, pthread_join(thread_handle.handle_, NULL));
 }
 
-// Mac has its own SetThreadPriority() implementation.
+// Mac has its own Set/GetThreadPriority() implementations.
 #if !defined(OS_MACOSX)
+
 // static
 void PlatformThread::SetThreadPriority(PlatformThreadHandle handle,
                                        ThreadPriority priority) {
-#if !defined(OS_NACL)
-  if (internal::HandleSetThreadPriorityForPlatform(handle, priority))
+#if defined(OS_NACL)
+  NOTIMPLEMENTED();
+#else
+  if (internal::SetThreadPriorityForPlatform(handle, priority))
     return;
 
   // setpriority(2) should change the whole thread group's (i.e. process)
   // priority. However, as stated in the bugs section of
   // http://man7.org/linux/man-pages/man2/getpriority.2.html: "under the current
   // Linux/NPTL implementation of POSIX threads, the nice value is a per-thread
   // attribute". Also, 0 is prefered to the current thread id since it is
   // equivalent but makes sandboxing easier (https://crbug.com/399473).
   DCHECK_NE(handle.id_, kInvalidThreadId);
   const int nice_setting = internal::ThreadPriorityToNiceValue(priority);
   const PlatformThreadId current_id = PlatformThread::CurrentId();
   if (setpriority(PRIO_PROCESS, handle.id_ == current_id ? 0 : handle.id_,
                   nice_setting)) {
     DVPLOG(1) << "Failed to set nice value of thread (" << handle.id_ << ") to "
               << nice_setting;
   }
+#endif  // defined(OS_NACL)
+}
+
+// static
+ThreadPriority PlatformThread::GetThreadPriority(PlatformThreadHandle handle) {
+#if defined(OS_NACL)
+  NOTIMPLEMENTED();
+  return ThreadPriority::NORMAL;
+#else
+  // Mirrors SetThreadPriority()'s implementation.
+  ThreadPriority platform_specific_priority;
+  if (internal::GetThreadPriorityForPlatform(handle,
+                                             &platform_specific_priority)) {
+    return platform_specific_priority;
+  }
+
+  DCHECK_NE(handle.id_, kInvalidThreadId);
+  const PlatformThreadId current_id = PlatformThread::CurrentId();
+  // Need to clear errno before calling getpriority():
+  // http://man7.org/linux/man-pages/man2/getpriority.2.html
+  errno = 0;
+  int nice_value =
+      getpriority(PRIO_PROCESS, handle.id_ == current_id ? 0 : handle.id_);
+  if (errno != 0) {
+    DVPLOG(1) << "Failed to get nice value of thread (" << handle.id_ << ")";
+    return ThreadPriority::NORMAL;
+  }
+
+  return internal::NiceValueToThreadPriority(nice_value);
 #endif  // !defined(OS_NACL)
 }
+
 #endif  // !defined(OS_MACOSX)
 
 }  // namespace base